The Chronic Dev Team released an untehtered version of their GreenPois0n jailbreak for iOS 4.2.1. Those who have been using an iOS 4.2 jailbreak on their iPhone 4 or iPad (certain older model iDevices can run the 4.2 jb untethered).
While running a tethered jailbreak, you no doubt noticed that you have to plug your device into your computer anytime you want to reboot. This can be a pain, especially if you are traveling and don’t have your laptop with you.
Also, rememebr to back up your phone before beginning, we are not responsible if something messes up and don’t install 4.2.1 if you are using UltraSnow to unlock, as per MuscleNerd:
“ultrasn0w unlockers *please* remember not to update to stock 4.2.1! Know exactly what to do to avoid a BB update!”
Now, you can skip that tedious process by installing this latest jb. Here’s how to do it (iPhone 4 or iPhone 3GS only):
1) Install iOS 4.2.1 if you haven’t already. This jailbreak won’t work with any other firmware version.
2) Go here to download GreenPois0n (Note: Mac only for now).
3) Plug your iPhone into your computer through USB.
4) Launch GreenPois0n.
5) Click the “jailbreak” button.
6) You will be given instructions to put your phone in DFU mode.
7) Once the jailbreak on your iPhone, you should see a new icon on Springboard (your main iPhone menu) for “Loader.”
8) Launch Loader to install Cydia.
9) Reboot your iPhone and you are ready to go.
MuscleNerd has also provided some insight as to how to get Cydia installed if you are having trouble via the loader:
“For those having trouble getting Cydia via the GP Loader, just let redsn0w install it (don’t choose the Monte option)”